Hello, info about quantum eraser experiment is at wikipedia and at http://grad.physics.sunysb.edu/~amarch/ [Broken] I want to express my view of last part of this experiment and want to discuss whether there really is an "erasure" or a breakdown of causality even in the delayed case. the way the coincidence counter measures the interference patterns really gets me thinking, cause i think there are some photons we ignore to measure which we shoudn't... please read ahead: scenario 1 -> WITHOUT the polarizer on p-way : -> one photon with 2f frequency hits BBO and two entangled photons get out each with f frequency. one partner goes through slits ( s-way ) goes through QWP1 and QWP2, which-path information becomes known, pattern is gone. scenario 2 -> WITH the polarizer on p-way : -> partner photon on p-way hits the polarizer, by %50 chance gets x-polarized and goes through. with %50 chance gets y-polarized and doesn't get through ! ( absorbed or reflected back ) *** the "doesn't get through" *** thing got me thinking: if photon on p-way goes through the polarizer it will hit the detector on p-way, other entangled photon on s-way will also hit the its detector and "coincidence counter" will "tick" BUT if photon on p-way doesn't go through, the other photon on s-way will STILL hit the detector and "coincidence counter" will NOT "tick", it will just ignore the photon on s-way and it will not be counted. I think if we were to count ALL the photons on s-way, interference patterns would still be "gone", "not present", even in the case the polarizer exists on p-way. the reason that the interference pattern SEEMS to come back is that; -> ALL the s-way photons do NOT form a pattern. ( since which-way info is known due to the presence of QWPs ) -> some specially selected (*) subset of photons on s-way DO form an interference pattern picture. the polarizer on p-way just tells the coincidence counter; -> which photon on s-way to count ( the partners of p-way photons that go through polarizer -> the specially selected subset ) -> and which to ignore, ( the partners of p-way photons that doesn't go through the polarizer ) polarizer on p-way just effect the coincidence counter and not the photon on s-way so there is no communication to s-photon here... and the interference pattern doesn't really come back ! so nothing is erased here. the interference pattern, that we observe after putting the polarizer, is NOT an actual interference pattern, it is just a picture of selected subset of all the photons on s-way, which do not form an interference pattern. am i right? any ideas?